Possibly, although since the parents didn't know about him, he could have at least tried to work something out when they moved in instead of just terrorizing their kid while he's noisily masturbating.
Maybe they knew all along, locked the monster into the room a long time ago, and when they got a son they thought "let's give him the empty room" because at that point they totally forgot about the monster because they internalized dehumanizing it and thought it was dead already. When they realized what they did, they just kept going, sure that the monster wouldn't complain because it doesn't have a voice. At least not one that would be heard.
But it came differently. The monster got to the point where it found a way to make itself heard and it did. The boy can't ignore it anymore and neither can his parents. When the boy was younger, they could talk it away as childish but now they can't ignor it anymore. The monster doesn't wait for a white savior, it helps itself.
It's either that or I'm totally overanalyzing. Time will show that I'm right. I'm on the right side of history.
What if - hear me out - the kid is the monster, and he's - hear me out - low key asking for permission to whack it loudly using a monster to deliver the news as proxy.